At present, in the field of special lighting (automobile lighting), two systems are generally employed: light distribution by a lens or a reflector or a combination thereof, wherein a typical light distribution system generally employs a single lens; effect of light distribution by an incident surface/an emergent surface is realized using a freeform-surface or a double freeform-surface. However, the single lens is inevitably subject to optical distortion, for example, chromatic aberration (chromatic dispersion), distortion (pincushion distortion or barrel distortion), spherical aberration or the like. Few studies are currently carried out for the impacts of using the single lens on color temperature upon LED light distribution.
In light distribution by a freeform-surface optical lens, the freeform-surface is mainly employed on the incident surface or the emergent surface, or the double freeform-surface that combines the both.
Till now, many designs are directed to illumination control and light energy distribution, whereas few designs are concentrated on lighting with uniform color temperature. Therefore, it is necessary to develop a double freeform-surface design for automobile lighting, to obtain a double freeform-surface lens to achieve lighting light spots with uniform color temperature.